1. Field of the Invention
The present invention relates to a phase-change heat dissipating device and a method for manufacturing it, and more particularly to a phase-change heat dissipating device with an excellent circulation of working liquid to improve a heat dissipation efficiency of the heat dissipating device, and a method for manufacturing the heat dissipating device.
2. Description of Related Art
As we know, a heat pipe is a conducting device which realizes conduction with working liquid therein, taking advantage of high conduction and good isothermal character. Therefore, it is widely used.
For these years, with the rapid development of electric technology, heat generated by electrical component increases highly. Therefore, phase-changed heat dissipating devices having good heat transfer performance have been widely used.
As shown in FIG. 5, commonly, a heat pipe comprises a sealed container 11 with internal walls coated with a capillary wick structure 4 that is filled with working fluid 13. The heat dissipating device 10 is commonly filled up the working liquid 13 after pressing the heat pipe to be vacuum. Then the container 11 is sealed when the wick structure 4 is fully filled with the working liquid 13. The heat pipe comprises a vaporizing portion 10a, an adiabatic portion and a condensing portion 10b. When the heat pipe absorbs heat at the vaporizing portion 10a thereof, working liquid 13 is vaporized to vapor, and a pressure gradient is formed in the heat pipe. This pressure gradient forces the vapor to flow from the vaporizing portion 10a to the condensing portion 10b where the vapor condenses and gives out its latent heat. The working fluid 13 is then returned back to the vaporizing portion 10a of the heat pipe via capillary forces developed in the wick structure 4.
A main function of the wick structure 4 in above circulation is to stimulate the return of the working liquid 13 to the vaporizing portion 10a. Commonly, sintered power and screen mesh are applied into a pipe to act as a wick structure. Another type of wick structure pipe is a grooved tube. However, the grooved tube is in high cost of the die and machine. It is difficult for the screen mesh to realize complete autoimmunization; thus, manpower cost is much high. A problem for the sintered power is that it needs a costly vacuum sinter furnace.
Therefore, it is desired to design a heat pipe which can improve heat dissipation efficiency and reduce manufacturing cost thereof.